1. Field of the Invention
This invention relates to display devices, and more particularly to a display device which is capable of presenting a stereoscopic display or simultaneously displaying two different images in separate angular directions, and which is used for an information equipment terminal.
2. Description of the Related Art
In a prior-art display device which is capable of stereoscopic display or two-screen display (in which two different images are simultaneously displayed in separate angular directions), a pair of light sources are arranged in the vicinities of both the end faces of a light guide plate whose surface is formed with a light extraction portion having a directionality in the emergent angle of light, by a roughening work or the like, and the light extraction portion is overlaid with a dual-side prism sheet and a transmission type liquid crystal panel, wherein the pair of light sources are alternately turned ON, and two different images are displayed on the transmission type liquid crystal panel in synchronism with the alternate turn-ON operations, thereby to present the stereoscopic display or two-image display (refer to, for example, T. Sasagawa, et al.: “Dual Directional Backlight for Stereoscopic LCD”, P 1-P 3, Society for Information Display '03 DIGEST (2003)).
The light guide plate of the prior-art stereoscopic display device or the prior-art display device displaying the two images in the separate angular directions, is constructed as stated above. Therefore, in light outputted from the light source at one end, light except direct light which emerges in a luminous intensity distribution for one image, from the light extraction portion in consequence of light guide, arrives at the other end and is reflected into reflection light which is guided in the opposite direction. When the reflection light emerges from the light extraction portion, it comes to have a luminous intensity distribution for the other image, and hence, the two images are observed in superposition. This has resulted in the problem that the contrast of the stereoscopic image or two different images lower.